DESCRIPTION: (Adapted from the Applicant's Abstract.) The goal of this research is to continue the implementation and testing of an algorithm that permits the accurate recording of the Auditory Brainstem Response (ABR) at very high repetition rates. In Phase I, it was shown that, through the use of this algorithm, it was possible to record averaged ABRs to click stimuli in anesthetized cats at repetition rates as high as 500 Hz, and to reconstruct the first 10ms of the ABR even though the stimuli were spaced only 2 ms apart and the ABRs overlapped one another. In Phase II the algorithm will be tested in ABR recordings in humans. Using a computer which records the A-D values from every sweep directly on the computer's hard disk will permit the efficacy of different analysis algorithms to be analyzed using identical data. Similarly, the same data will be digitally filtered and then re-analyzed using different sets of filter characteristics, rather than pre-filtering the data prior to averaging, as was done in Phase I. Using the data obtained, the authors will design a clinical testing procedure making use of this algorithm. The improved method of recording the ABR will increase the sensitivity of ABR testing in a wide variety of diseases, including HIV infection and AIDS.